The flowers of the Kalmia latifolia, or mountain kalmia, a native evergreen, very abundant on the side of barren hills and the rocky margins of rivulets, are especially deserving of attention. The corollas of the kalmia are rotate or wheel-shaped, and have ten stamens, the anthers of which, before the flowers expand, are contained in ten little cavities or depressions in the side of each corolla, where they are secured by a viscid secretion. When the corollas open, the filaments of the stamens are bent back by this confinement of their anthers like so many springs, in which condition they remain until the pollen in the anther cells becomes ripe and absorbs the secretion. The anthers, becoming suddenly liberated by this means from their cavities, fly up with such force as to eject their pollen on the pistil. The slightest touch with the point of a needle, or the feet of an insect crawling over their filaments, is sufficient to produce the same effects when the pollen is mature. Fig. 2 shows, at _a_, the fully expanded flower with the confined anthers; at _b_, the flower after the anthers have discharged their pollen. [Illustration: Fig. 2.] When the stamens and pistils are together in the same flower, it is designated as hermaphrodite, and complete; but, if the flower contains only one of these organs, it is termed unisexual, and, in this case, it is either male or female, according as it is composed uniquely of stamens, or male sexual organs, or of pistils, or female sexual organs. This separation of the sexual organs in flowers is of very frequent occurrence. The greater portion of our forest trees, and many herbaceous plants and shrubs, have unisexual flowers. Sometimes the stamens and pistils are situated in separate flowers on the same plant. When this is the case, the staminate flowers are generally situated above the pistillate. The Indian corn exemplifies this arrangement. It is well known that the flowering panicle at the summit of the stem does not produce corn; these are the staminiferous flowers from whose anthers descend clouds of pollen on the threadlike pistils forming the silky tuft beneath. Without this pollen, the corn in the lower spike would not ripen; hence the evident design of nature in placing the pistillate below the staminate spike of flowers.